All of These Fantastic Race Cars Started as Road Cars

FIA GT3: It's the brilliantly simple formula that transforms fearsome sports cars into even fiercer racing machines. GT3 cars are, first and foremost, real cars—no Camrys with pushrod V8s here. Modifications generally involve deleting weighty niceties and adding safety cages, cartoonish fenders, carbon-fiber bodywork, slicks, and rear wings the size of surfboards. GT3 also allows for an amazing degree of diversity. Air restrictors and ballast keep output to about 500 hp and dry weight to around 2800 pounds, but the rules don't dictate engine displacement or layout. That makes it relatively easy to build a GT3 car, as more than a dozen manufacturers have. They're raced at Bathurst in Australia, Daytona, the Nürburgring, and in series like IMSA's WeatherTech SportsCar Championship and the SCCA's Pirelli World Challenge. It's Gran Turismo brought to life. Here are a few of our favorites.

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AUDI R8 LMS

Brecht Dencanq

GT3 rules prohibit all-wheel drive, forcing Audi to build something we've always wanted: a leaner and meaner rear-wheel-drive R8. Weight distribution shifts from 50/50 to a Porsche 911–esque 46 percent rear bias. Otherwise, the separation between road and track is tantalizingly thin. The R8 LMS's aluminum and carbon-fiber chassis is randomly chosen from the assembly line, and the 5.2-liter V10 needs few modifications, although the Germans do handpick each engine based on dyno figures.

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CADILLAC ATS-V.R

Brian Cleary/Getty Images

The Cadillac ATS is the least expensive road car in GT3 competition. Its conversion is one of the most extensive, including 47.9 feet of steel tubing for the safety cage. Readying the Caddy's 3.6-liter twin-turbo V6 alone takes five full days. It's worth it, as the ATS-V.R sounds satanic. "Like it's ripping holes in the air," confirms Cadillac factory driver Andy Pilgrim. "I love it."

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LEXUS RC F GT3

Nat Twiss

It looks like it should decimate everything in its path, but early forays have been humbling. After running more than 10 seconds off pace at the Nürburgring, Lexus pushed the RC F's planned debut to late 2016. We doubt power is the problem, as the 5.0-liter V8 already produces 467 hp in stock form.

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BENTLEY CONTINENTAL GT3

James Lipman

Even with the lighter 4.0-liter V8 rather than the 6.0-liter W12, the Bentley Continental needed considerably more than a simple weight-loss program to get itself into GT3 fighting condition; it required the automotive equivalent of bariatric surgery. To reduce from its starting weight of some 5050 pounds to a race-ready 2866 pounds, Bentley had to remove roughly a Chevy Spark's worth of tonnage. "The first to go are the foot massagers," factory Bentley racer Guy Smith says with a laugh. "All the luxury weighs a considerable sum. We save almost 50 kilos [110 pounds] per door by using lightweight materials. But it still has the Bentley feel from inside. And I'm told it's quite imposing to see in one's rearview mirrors."

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NISSAN GT-R NISMO GT3

Brett Decancq

The GT-R has taken a while to reach its competitive stride. Its 3.8-liter twin-turbo V6 is a technical marvel, but the car is tall and heavy. And although the GT-R has shed AWD, challenges remain. "We're a big, front-engine car, so we make up our time in the corners with big dive planes, and we make it up on the straights with giant turbos," driver James Davison says. "Godzilla's coming for you, baby."

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MERCEDES-AMG GT3

Daimler AG

Behind the AMG's throwback, Panamericana-style grille roars a throwback engine: the naturally aspirated 6.2-liter V8 we know and love from the last-generation SLS gullwing. It survives here because Mercedes already adapted it for racing in the old SLS GT3 car. Not surprisingly, the AMG GT3 sounds like artillery fire shattering the Ardennes.

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MCLAREN 650S GT3

Chris Brown

McLaren's 650S, already a lightweight, purposeful sports car with a twin-turbo 3.8-liter V8, easily becomes the 650S GT3. Those who work on the Woking race car say its carbon-fiber chassis is like a tub for a Le Mans prototype and that the rest of it is like an F1 car with fenders. The steering wheel, derived from the one in the 2008 McLaren MP4-23 F1 car, can be equipped with a hand-clutch system.

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